Known stoppers for holes via which X-ray inspection means are inserted into pipes, e.g., have closed ends and are welded onto the corresponding pipe or apparatus after X-ray inspection of the weld(s) to be inspected. They cannot be used again if welds need to be inspected at a later time after a given period of operation. The weld must be removed before unscrewing the stopper. This could damage the surface of the tube or apparatus to which the stopper is fitted. When further inspection is needed, another opening is therefore made in the wall, then said opening is closed after inspection by means of a new stopper which likewise cannot be used again. This is a relatively long and expensive operation and causes the wall to be successively pierced at points which are close to one another.
The present invention aims to remedy these drawbacks and to provide a stopper for such inspection openings which enable an X-ray source to be inserted inside a pipe or other apparatus as often as may be required and in a very short time.
The present invention provides a stopper for an inspection hole to give an X-ray inspection probe access to the inside of a pipe or other apparatus wherein the stopper comprises a cylindrical outer component having an open end and an inside screw thread, said outer component being welded to the wall of said pipe or other apparatus and leaving an outside end protruding therefrom, and a cylindrical inner component having a blind hole and an outside screw thread, said inner component being screwed into the inside screw thread of the outer component and having an outside end which is welded around its periphery to the projecting outside end of the outer component, said blind hole being equipped with means which allow the inner component to be unscrewed from the outer component after the weld joining the outside ends of said components has been broken.
Preferably, said means allowing the inner component to be unscrewed are constituted by an inside screw thread on said cylindrical inner component, the pitch of the screw thread being of the opposite hand to the pitch of its outside thread thereby enabling said second component to be unscrewed by means of a screw of matching pitch.